Filter body for particle filter

ABSTRACT

In a filter pocket for a particle filter with a pocket part, comprised of a gas-permeable support material coated with a sintered metal powder, and with a connection part connected with the pocket part and provided for welding together with a holding element, the pocket part and the connection part together form a closed volume and the connection part is comprised of a gas-impermeable material.

The invention relates to a filter pocket for a particle filter for the elimination of particles contained in an exhaust gas stream, in particular in an exhaust gas system of an internal combustion machine, with a pocket part and with a connection part connected to the pocket part. The invention furthermore relates to a particle filter and a method for the production of a filter pocket for a particle filter.

EP 0 331 885 B1 describes an exhaust gas filter for eliminating noxious components of exhaust gases, which comprises a filter body of a high temperature-resistant sintered material with a multiplicity of inlet and outlet channels.

DE 101 28 938 A1 discloses a particle filter comprising several filter pockets and the exhaust gas stream is purified during the inflow into the filter pockets comprised of sintered metal or coated with sintered metal powder.

One problem encountered in the production of such filter pockets for particle filters is the connection of the filter pockets with a holding element, on which several filter pockets are disposed to form the particle filter. Especially, if the material of the filter pocket is to be welded with the holding element, problems are regularly encountered with respect to the long fatigue strength of such a welded connection. Moreover, in that region of the filter pocket at which it is to be attached on the holding element, a high deformation degree is required, which, however, leads to difficulties in the porous gas-permeable material.

The present invention therefore addresses the problem of providing a filter pocket for a particle filter, in which the simple connection of several filter pockets with a holding element is given.

This problem is solved according to the invention through the characteristics listed in claim 1.

The pocket part comprised of a gas-permeable support material coated with a sintered metal powder, ensures the filter action of the filter pocket according to the invention by making possible the deposition of particles on the same. The connection part, on the other hand, which, according to the invention is comprised of a deformable gas-permeable material, makes possible the simple connection of the filter pocket with a holding element or the like. Moreover, thereby that is it comprised of a different material more readily deformed than the pocket part, the connection part can with significantly lower expenditures be provided with a geometric shape, which makes possible sealing the connection parts against one another, if these are disposed in a particle filter.

The function of the filter pocket according to the invention is ensured thereby that the pocket part and the connection part together from a volume into which flows the exhaust gas stream, is filtered and from which it leaves the volume again.

A first embodiment of the invention can provide that the pocket part and the connection part are two separate structural parts connected by welding. While it is also required in such an embodiment that the support material in the present case be welded to the connection part, however, a considerably larger area is available for this purpose than is the case with the problematic connections according to prior art, such that considerably fewer difficulties need to be expected when welding the connection part to the pocket part.

A second embodiment can provide that the pocket part and the connection part are developed of an integral material. This embodiment has the advantage that it is not required to connect the connection part and the pocket part. It is only necessary to ensure that the pocket part is gas-permeable and coated with a sintered metal powder, and that the connection part is comprised of a formable gas-impermeable material.

This requirement can, for example, be accounted for thereby that the connection part and the pocket part are formed of an integral expanded sheet metal with expanded regions and non-expanded regions, with the expanded regions of the expanded sheet metal forming the pocket part and the nonexpanded regions of the expanded sheet metal forming the connection part.

It is also optionally possible to implement the filter material only in the proximity of the deformation such that a deformation is attained in the region of the head of the filter pocket without tearing open the filter area.

A particle filter for eliminating particles contained in an exhaust gas stream, in particular in an exhaust gas system of an internal combustion engine, with several filter pockets one disposed next to the other is evident in claim 8.

In claims 12 and 14 can be found two alternative methods for the production of a filter pocket according to the invention for a particle filter.

Further advantageous embodiments and further developments of the invention are evident in the remaining dependent claims as well as in conjunction with the embodiment examples shown in principle in the following in the drawing. Therein depict:

FIG. 1 a first embodiment of the filter pocket according to the invention,

FIG. 2 a second embodiment of the filter pocket according to the invention,

FIG. 3 a section along line III-III of FIG. 2, and

FIG. 4 a particle filter with several filter pockets developed according to the invention.

FIG. 1 shows a filter pocket 1 for a particle filter 2 depicted in FIG. 4. The particle filter 2 is provided for the elimination of particles contained in an exhaust gas stream, in particular in an exhaust gas system of an internal combustion engine. Neither the internal combustion engine nor its exhaust gas system are depicted.

The filter pocket 1 comprises a pocket part 3 and a head part or connection part 4, which together form a volume. The pocket part 3 in the present case includes two side walls 5, which extend substantially parallel to one another in the longitudinal direction denoted by arrow A of the filter pocket 1 as well as also in the transverse direction denoted by arrow B of the filter pocket 1. In the direction of arrow B a minimal conicity of the pocket part 3 is evident. With the exception of the lower termination edge as well as the minimal conicality in the transverse direction, consequently an approximately rectangular cross section shape of the pocket part 3 results.

The pocket part 3 is comprised of a gas-permeable support material, for example a woven wire cloth, coated with a sintered metal powder. When coating with the sintered metal powder the voids the woven wire cloth are filled. Due to the porosity of the pocket part 3, the exhaust gas can flow through the side walls 5 into the filter pocket 1 and therewith into the volume formed by the pocket part 3 and the connection part 4 and can leave the same at an axial opening 6 of the connection part 4, which extends over the entire cross section of the connection part 4. Due to the coating with the sintered metal powder, the side walls 5 assume herein the purification action by filtering out particles in the exhaust gas stream. However, it is understood that in principle also a direction of flow is possible which is reverse to the described preferred direction of flow.

The connection part 4, which according to the embodiment of FIG. 1 represents a structural part separate from the pocket part 3, is connected with the same by welding, and FIG. 1 shows the condition in which the connection part 4 is not yet connected with the pocket part 3. In order to be able to weld the connection part 4, and consequently the filter pocket 1, with a holding element 7 shown in FIG. 4, of the particle filter 2, the connection part 4 is preferably comprised of a gas-impermeable impervious material with a substantially smooth surface, preferably of a temperature-resistant sheet metal. However, it can also be provided that the pocket part 3 and the connection part 4 be developed integrally of expanded metal. In cross section the connection part 4 has the form of a wedge, whose function will be explained in further detail with reference to FIG. 4.

The filter pocket 1 according to FIG. 1 can be produced in the following manner: first, the gas-permeable support material is coated with the sintered metal powder and subsequently reshaped into the pocket part 3. In spite of the above described porosity of the pocket part 3, no damage of it occurs during this reshaping The pocket part 3 acquires at its lower side a longitudinal seam, which can be welded, for example. Instead of a complete reshaping, the two side walls 5 can also be welded together at two edges. The connection part 4 is formed from the gas-impermeable material and the pocket part 3, and the connection part 4 are subsequently connected with one another for example by welding.

In FIG. 2 an alternative embodiment of the filter pocket 1 is shown in a position rotated by 90° compared to FIG. 1. The pocket part 3 and the connection part 4 are formed of an integral expanded sheet metal, which consists of expanded regions, which are gas permeable, and non-expanded regions, which are gas-impermeable. The expanded regions form the pocket part 3 and the non-expanded regions form the connection part 4. The term expanded metal and the method employed for the production of the same are generally known to a person skilled in the art and for that reason it is not necessary to explain these further.

The filter pocket 1 according to FIG. 2 can be produced in the following manner: The expanded sheet metal is first provided with expanded regions having voids and non-expanded regions without voids. Thereupon the expanded regions are coated with the sintered metal powder, sintered and subsequently the expanded sheet metal is reshaped into the filter pocket 1, with the expanded regions forming the pocket part 3 and the non-expanded regions the connection part 4, which is provided with the holding element 7 for connecting the filter pocket 3. The sintered metal powder is automatically deposited at the voids of the expanded regions during the coating of the expanded sheet metal and, in contrast, cannot become deposited on the non-expanded regions, since there are no voids here.

In both embodiments of the filter pocket 1 the transition from the rectangular shape of the pocket part 3 to the wedge shape of the connection part 4 is carried out smoothly and can extend over a relatively long region of the connection part 4, to facilitate the above described reshaping processes.

FIG. 3 shows a section through the pocket part 3 of the filter pocket 1 from FIG. 2. However, a section through the filter pocket 1 according to FIG. 1 could have a similar or even identical appearance, since there are no significant geometric differences between the pocket part 3 of FIG. 1 and that of FIG. 2. This applies essentially also to the connection part 4. In the interior of the pocket part 3 spacer elements 8 can be seen disposed on the side walls 5, which ensure that the exhaust gas pressure cannot press the side walls 5 together and consequently reduce the volume within the filter pocket 1. Therewith a satisfactory volume within the filter pocket 1 is always secured and the stability of the same is ensured. The spacer elements 8 are implemented such that either opposing spacer elements 8 are in contact with one another or they are in contact with the particular opposing side wall 5. In FIG. 3 both examples are depicted. In the present case the spacer elements 8 are developed as knobs. However, the spacers can also be webs or ribs extending in the longitudinal and/or transverse direction of side walls 5. Such webs or ribs, not shown, can be implemented, for example, as axially extending embossments or beads in one of the side walls 5, with the knobs of the opposing side wall 5 contacting such a bead.

FIG. 4 depicts the particle filter 2 comprised of several filter pockets 1 disposed radially one next to the other, which are disposed on one side on a closure or sealing element 9 and on the opposing side on an outer ring 10. Consequently the outer ring 10 forms the holding element 7 with which several filter pockets 1 can be held for forming the particle filter 2. Due to their shape, the filter pockets 1 sustain themselves in their interior region. On the opposite side of the outer ring 10 a similar structural part can be disposed, to attain greater rigidity of the particle filter 2.

FIG. 4 shows furthermore that the filter pockets 1 on the side opposite to the outer ring 10 are spaced apart from one another in the circumferential direction, such that the exhaust gas stream without problems can flow in between the individual filter pockets 1 and in the generated interspaces ash and other particles can collect. However, the connection parts 4, as already described above, are widened or have a wedge form, such that on that side of the particle filter 2, on which the sealing element 9 and the outer ring 10 are located, the exhaust gas stream is prevented from flowing through between two filter pockets 1. This forces the exhaust gas stream to flow into the pocket parts 3 and to leave the filter pockets 1 through the openings 6 of the connection parts 4, which ensures high good purification action of the particle filters 2. The sealing element 9 consequently blocks off the gas path and excludes that the gas can escape at a site different from the openings.

To increase the imperviousness in this outlet region of the particle filter 2, the connection parts 4 are, in addition, welded with one another as well as with the sealing element 9 and the outer ring 10. For this purpose corresponding recesses can be disposed on the outer ring 10, in order to ensure corresponding guidance for the connection parts. The filter pockets 1 can also have corresponding recesses for the connection with the outer ring 10. In this context, laser welding is for example a suitable welding method. However, it is understood that WIG welding, rolled-seam welding or another welding method can also be suitable. 

1. Filter pocket (1) for a particle filter (2) for eliminating particles contained in an exhaust gas stream, in particular in an exhaust system of an internal combustion engine, with a pocket part (3) comprised of a gas-permeable support material coated with a sintered metal powder, and with a connection part (4) connected with the pocket part (3), which connection part is provided for being welded together with a holding element (7), and the pocket part (3) and the connection part (4) together form a volume, and the connection part (4) is comprised of a gas-impermeable material.
 2. Filter pocket as claimed in claim 1, characterized in that the connection part (4) is comprised of a temperature-resistant sheet metal.
 3. Filter pocket as claimed in claim 1 or 2, characterized in that the pocket part (3) and the connection part (4) are two separate structural parts connected with one another by welding.
 4. Filter pocket as claimed in claim 1 or 2, characterized in that the pocket part (3) and the connection part (4) are developed from an integral material.
 5. Filter pocket as claimed in claim 4, characterized in that the pocket part (3) and the connection part (4) are formed of an integral expanded sheet metal with expanded regions and non-expanded regions, and the expanded regions of the expanded sheet metal form the pocket part (3) and the non-expanded regions of the expanded sheet metal form the connection part (4).
 6. Filter pocket as claimed in one of claims 1 to 5, characterized in that the pocket part (3) has two side walls (5), which extend substantially parallel to one another in the longitudinal and/or transverse direction (A, B) of the filter pocket (1).
 7. Filter pocket as claimed in claim 6, characterized in that within the pocket part (3) spacer elements (8) are disposed between the side walls (5).
 8. Particle filter (2) for eliminating particles contained in an exhaust gas stream, in particular in an exhaust gas system of an internal combustion engine, with several filter pockets (1) according to one of claims 1 to 7 disposed one next to the other.
 9. Particle filter as claimed in claim 8, characterized in that the filter pockets (1) are disposed radially, and the filter pockets (1) are disposed on an outer ring (10) as a holding element (7) and the gas path is blocked off by means of a sealing element (9).
 10. Particle filter as claimed in claim 8 or 9, characterized in that the connection parts (4) of the filter pockets (1) are welded together with the outer ring (10).
 11. Particle filter as claimed in claim 8 or 9, characterized in that the filter pockets (1) are spaced apart from one another in the circumferential direction.
 12. Method for the production of a filter pocket (1) for a particle filter (2) for eliminating particles contained in an exhaust gas stream, in particular in an exhaust gas system of an internal combustion engine, with the following method steps: a gas-permeable support material is coated with a sintered metal powder, from the coated support material a pocket part (3) is formed, from a gas-impermeable material a connection part (4) is formed for connecting the filter pockets (1) with a holding element (7), the pocket part (3) and the connection part (4) are connected with one another.
 13. Method as claimed in claim 12, characterized in that the pocket part (3) and the connection part (4) are welded together.
 14. Method for the production of a filter pocket (1) for a particle filter (2) for eliminating particles contained in an exhaust gas stream, in particular in an exhaust gas system of an internal combustion engine, with the following method steps: an expanded sheet metal is provided with expanded regions and non-expanded regions, the expanded regions are coated with a sintered metal powder, the expanded sheet metal is reshaped into a filter pocket (1) and the expanded regions form a pocket part (3) and the non-expanded regions a connection part (4) for connecting the filter pockets (1) with a holding element (7). 